From cbfa58d56c3ca59538bf23e30105ce27ed5ef948 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Wed, 4 Sep 2024 12:47:03 +0100
Subject: ash: optimise running of scripts (2)
Commit 4b7b4a960 (ash: optimise running of scripts) avoided creation
of a process when running a script. There's another case where we
can do the same: if the script is being run from a FS_SHELLEXEC
shell.
- Check the necessary conditions for this to happen.
- Allocate two extra slots in the argv array for FS_SHELLEXEC.
- Set the index of the script file in the argv array. Without this
the test 'pidof this' failed because the command name hadn't been
correctly set.
Adds 80-96 bytes.
---
include/mingw.h | 1 +
libbb/appletlib.c | 7 +++++++
shell/ash.c | 26 ++++++++++++++++++--------
3 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/include/mingw.h b/include/mingw.h
index ed7884e39..65940b40b 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -667,3 +667,4 @@ enum {
ADMIN_ENABLED = 2
};
int elevation_state(void);
+void set_interp(int i) FAST_FUNC;
diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index 97dfb3df8..1ff7fe6c8 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -394,6 +394,13 @@ bool re_execed;
static int interp = 0;
char bb_comm[COMM_LEN];
char bb_command_line[128];
+
+# if ENABLE_FEATURE_SH_STANDALONE
+void FAST_FUNC set_interp(int i)
+{
+ interp = i;
+}
+# endif
#endif
diff --git a/shell/ash.c b/shell/ash.c
index 2e4181b3f..d9a7bee83 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9099,6 +9099,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
#endif
{
#if ENABLE_PLATFORM_MINGW32 && ENABLE_FEATURE_SH_STANDALONE
+ struct forkshell *fs = (struct forkshell *)sticky_mem_start;
interp_t interp;
#endif
#if ENABLE_FEATURE_SH_STANDALONE
@@ -9106,7 +9107,6 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
# if ENABLE_PLATFORM_MINGW32
/* Treat all applets as NOEXEC, including the shell itself if
* this is a FS_SHELLEXEC shell. */
- struct forkshell *fs = (struct forkshell *)sticky_mem_start;
if (applet_main[applet_no] != ash_main ||
(fs && fs->fpid == FS_SHELLEXEC)) {
run_noexec:
@@ -9152,21 +9152,28 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
add_win32_extension((char *)cmd);
# if ENABLE_FEATURE_SH_STANDALONE
- /* If nfpath is non-NULL, evalcommand() has determined this
- * command doesn't need a fork(). If the command is a script
- * with an interpreter which is an applet we can run it as if
- * it were a noexec applet. */
+ /* If nfpath is non-NULL evalcommand() has determined this
+ * command doesn't need a fork(). Even it's NULL we can
+ * possibly avoid a fork if this is a FS_SHELLEXEC shell. */
+ if (nfpath == NULL && (fs && fs->fpid == FS_SHELLEXEC))
+ nfpath = pathval();
+
+ /* If nfpath is non-NULL and the command is a script with an
+ * interpreter which is an applet, we can run it as if it
+ * were a noexec applet. */
if (nfpath && parse_interpreter(cmd, &interp)) {
applet_no = find_applet_by_name_for_sh(interp.name, nfpath);
if (applet_no >= 0) {
argv[0] = (char *)cmd;
- /* evalcommand() has added two elements before argv */
+ /* evalcommand()/spawn_forkshell() add two elements before argv */
if (interp.opts) {
argv--;
argv[0] = (char *)interp.opts;
}
argv--;
cmd = argv[0] = (char *)interp.name;
+ /* Identify the index of the script file in argv */
+ set_interp(1 + (interp.opts != NULL));
goto run_noexec;
}
}
@@ -16842,7 +16849,8 @@ argv_size(struct datasize ds, char **p)
ds.funcstringsize += align_len(*p);
p++;
}
- ds.funcblocksize += sizeof(char *);
+ // Allow two extra elements for tryexec().
+ ds.funcblocksize += 3 * sizeof(char *);
}
return ds;
}
@@ -16856,6 +16864,8 @@ argv_copy(char **p)
#endif
if (p) {
+ // Allow two extra elements for tryexec().
+ funcblock = (char *) funcblock + 2 * sizeof(char *);
while (*p) {
new = funcblock;
funcblock = (char *) funcblock + sizeof(char *);
@@ -16866,7 +16876,7 @@ argv_copy(char **p)
new = funcblock;
funcblock = (char *) funcblock + sizeof(char *);
*new = NULL;
- return start;
+ return start + 2;
}
return NULL;
}
--
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